Do I lecture too quickly?
My mathematical work is supported by NSF grant DMS-1100784.
If you are taking a class from me then you should find a functioning
link to it below (with course information, homeworks, and so on).
If several days go by without a response to email,
I am probably away from home.
Number theory and representation theory seminar
Analytic number theory, algebraic number theory,
arithmetic geometry, automorphic forms, and even some things
not beginning with the letter "a". It's a big subject.
Schedule and notes for the 2014-15 Seminaire Scholze
Schedule and notes for the 2013-14 Seminaire Jacquet-Langlands
Schedule and notes for the 2012-13 Seminaire Shimura
Schedule and notes for the 2011-12 Seminaire Darmon
Schedule and notes for the 2010-11 Mordell seminar
Schedule & notes for the 2009-10 modularity lifting seminar
Links to current courses:
Math 154 (Undergraduate algebraic number theory)
Math 249C (Abelian varieties)
Here are handouts and homeworks from some past undergraduate courses:
Undergraduate algebraic geometry
Here are handouts and homeworks from some past graduate courses:
Linear algebraic groups I ,
Linear algebraic groups II ,
Linear algebraic groups III ,
Class field theory,
Compact Lie groups
Some differential geometry
I once taught an introductory differential geometry course
and was rather disappointed with the course text,
so I went overboard (or crazy?) and wrote several hundred pages of stuff to supplement
If you are learning elementary differential geometry, maybe you'll find
some of these handouts to be interesting. Most likely I will never again
teach such a course.
Some mathematicians are entirely self-created;
for the rest of us, assistance and encouragement
early on is helpful. These programs do an excellent job in that direction.
First, some caveats.
0. Links to files undergoing revision may be temporarily disabled.
1. If you want to know where something below was published
(if it has appeared in print), then please look on MathSciNet.
2. Someday I should join the 21st century and post
papers on the arxiv, at least after I can no longer make changes
to the version to be published. In particular, I should post
my old papers that have already appeared. Unfortunately (?), I tend
to rewrite things too many times and don't wish to keep
posting revision on top of revision on the arxiv. Posting things
here (even in far-from-final state) partially compensates for my
pedantry, I hope.
Are you looking for how to get a copy of
the pseudo-reductive book with Gabber and Prasad? Or a draft copy of the CM book with Chai and Oort?
If so, scroll down to the "Book" section below.
Classification of pseudo-reductive groups
Reductive group schemes (notes for "SGA3 summer school").
This proves main results from SGA3 using Artin's work and the dynamic method from "Pseudo-reductive groups" to simplify proofs.
Here is a  link
to some other notes from the summer school, inspired by a lecture given there by
B. Gross on non-split groups over the integers, and a related  file by J.-K. Yu providing
computer code used in some of the computations therein.
Algebraic independence of periods and logarithms of Drinfeld modules (by C-Y. Chang, M. Papanikolas).
I provided the appendix (a pseudo-application of pseudo-reductive groups).
Lifting global representations with local properties
Universal property of non-archimedean analytification.
Descent for non-archimedean analytic spaces (with M. Temkin).
Finiteness theorems for algebraic groups over function fields.
Moishezon spaces in rigid geometry.
Nagata compactification for algebraic spaces (with M. Lieblich, M. Olsson).
Arithmetic properties of the Shimura-Shintani-Waldspurger correspondence
(by K. Prasanna).
I provided the appendix.
Non-archimedean analytification of algebraic spaces (with M. Temkin).
Chow's K/k-image and K/k-trace, and the Lang-Neron theorem
This largely expository note improves the non-effective classical version of
the Chow regularity theorem, and generally uses infinitesimal methods and
flat descent to replace Weil-style proofs that I could not understand.
It is also cited in "Root numbers and ranks in positive characteristic" below.
Prime specialization in higher genus II (with K. Conrad and R. Gross).
Prime specialization in higher genus I (with K. Conrad).
Higher-level canonical subgroups in abelian varieties.
Modular curves and rigid-analytic spaces.
Relative ampleness in rigid-analytic geometry.
Root numbers and ranks in positive characteristic
(with K. Conrad and H. Helfgott).
Arithmetic moduli of generalized elliptic curves.
Edixhoven has a different approach to these matters
when the moduli stacks are Deligne-Mumford.
Prime specialization in genus 0 (with K. Conrad and R. Gross).
Modular curves and Ramanujan's continued fraction (with B. Cais).
A short erratum to this paper.   pdf
"On quasi-reductive group schemes"
(by G. Prasad and J-K. Yu).
I provided the appendix.
The Möbius function and the residue theorem (with K. Conrad).
This is a companion to "Prime specialization in genus 0"
J1(p) has connected fibers
(with S. Edixhoven and W. Stein).
Finite-order automorphisms of a certain torus.
Gross-Zagier revisited (with appendix
by W. R. Mann).
Power laws for monkeys typing randomly: the case of unequal
probabilities (with M. Mitzenmacher).
Approximation of versal deformations (with A. J. de Jong).
A modern proof of Chevalley's theorem on algebraic groups.
Component groups of purely toric quotients
(with W. Stein).
On the modularity of elliptic curves over Q
(with C. Breuil, F. Diamond, R. Taylor).
Inertia groups and fibers.
Correction to "Inertia groups and fibers"
Irreducible components of rigid spaces.
Modularity of certain potentially Barsotti-Tate
representations (with F. Diamond and R. Taylor).
Remarks on mod-ln representations with
l = 3, 5
(with S. Wong).
Ramified deformation problems.
Finite group schemes over bases with low ramification.
Here are some books, pre-books, etc.
Complex multiplication and lifting problems (with C-L. Chai, F. Oort)
order while supplies last!
(this link might be behind a firewall; the ISBN number is ISBN-10: 1-4704-1014-1)
Pseudo-reductive groups (with O. Gabber, G. Prasad)
order while supplies last!
Grothendieck duality and base change
Clarifications and corrections to "Grothendieck duality and base change"
An addendum to Chapter 5 of "Grothendieck duality and base change"
My book on Galois representations and modular forms is
still undergoing revisions. (It
is now shorter than it was before, with much better proofs;
if you have an earlier version, please burn it.) The
following link has been disabled.
Modular forms and the Ramanujan conjecture
Here is a very rough draft of a book with M. Lieblich (more to be
included, such as exercises, applications to the theory of
the monodromy pairing and the p-adic good reduction criterion, etc., and much to
be revised). Whoops, the link is now disabled (due to
some strange errors that need to be fixed).
Galois representations arising from p-divisible groups
Here are some expository things I have written.
These may be updated without warning. Links to files undergoing
revision may be temporarily disabled.
The basic guiding principles for deciding what to write up and post here
1. Interesting (to me?) alternative proofs
of known results, or explanations of
important topics that can be difficult for beginners
to learn are fair game.
(As the literature improves, I may augment postings
2. With all due respect to
the role of Andre Weil in the development of
algebraic geometry, nobody should ever again have to
read Weil's "Foundations of algebraic geometry": EGA must be an adequate
logical starting point for the subject. Hence, if there is
an important, interesting, or useful theorem
whose published proofs use pre-Grothendieck
methods in such an essential way so as to
render them impenetrable to later generations
(or to me?),
and if I have a need to understand
why the theorem is true and consequently I figure out a scheme-theoretic
proof, then I'll try to write it up.
The structure of solvable groups over general fields. pdf
These are notes that mildly revise Appendix B of the "pseudo-reductive" book, to accompany some lectures at the 2011 "SGA3 summer school" in Lumimy.
Some notes on topologizing the adelic points of schemes,
unifying the viewpoints of Grothendieck and Weil.
Some lecture notes on p-adic Hodge theory, from a course
I taught with Olivier Brinon at the 2009 CMI summer school on Galois
representations. It is undergoing regular revision; not yet in final form (so corrections
2007 Arizona Winter School lectures on rigid geometry
This appeared as a chapter in a book produced by the Winter School.
Formal GAGA for Artin stacks.
The paper "On proper coverings of Artin stacks" by M. Olsson gives
a different point of view on this topic.
Rosenlicht's unit theorem
Rosenlicht proved an extremely interesting theorem on
the structure of units on a product of varieties. Since
Rosenlicht's proof doesn't address the generality cited
without proof in SGA7, and it was written in archaic terminology,
this short note gives a "modern" treatment (and eliminates
the assumption on existence of rational points).
Integration in elementary terms
Have you told your calculus class that the Gaussian integral cannot
be computed in elementary terms, or likewise for elliptic integrals
when teaching a course on Riemann surfaces, but you personally have no idea how
such a (useless but pretty) result is proved? If so, then you
should definitely read Rosenlicht's article "Integration in finite terms"
in volume 79 of
the American Mathematical Monthly (in 1972). But if you have to explain
the proof to talented high school students, this short note (based on a talk
I gave to such students at CMI) may be helpful.
Keel-Mori theorem via stacks.
In this note, we use stacks instead of groupoids to give
a streamlined proof of the Keel-Mori existence theorem
for coarse moduli spaces (useless bonus: noetherian hypotheses eliminated).
Minimal models for elliptic curves.
The book "Algebraic geometry and arithmetic curves"
by Q. Liu treats much (but not all) of this material.
WARNING: these notes are essentially written
in the context of topology and
etale sites; this is adequate for arithmetic
applications (potential semistability of l-adic
cohomology via alterations) but is woefully inadequate
for geometric applications (quasi-coherent cohomology on Artin stacks).
The level of generality
(and aspects of the writing style)
will be much-improved in the next version
so that the notes suffice to treat geometric applications too.
Descent for coherent sheaves on rigid-analytic spaces.
The paper "Coherent modules and their descent on relative
rigid spaces" by S. Bosch and U. Görtz gives a different approach
to this topic (pre-dating mine, as I found out later).
Nagata's compactification theorem (via schemes).
This is a detailed exposition of some
private notes of Deligne.
The paper "On compactification of schemes" by W. Lütkebohmert
gives a different approach to this topic in the noetherian case,
but Deligne's approach gives some striking results of general
interest for rational maps.
If you can understand what is going on in
Nagata's original paper then you are either very old
or very smart (or both!). These notes were eventually published
in Journal of the Ramanujan Math Society (vol. 22, 2007).
In the published version there was a tiny mistake in
one definition in the middle of a long proof, but this error
was localized and easy to fix. There was also a tiny error
in the appendix (never used in the main text). Here is the official erratum (but the
above link is to a file in which the errors are corrected).
The classical Riemann-Hilbert
Some exercises on group schemes and p-divisible groups.
Homework 1: pdf.
Homework 2: pdf.
Homework 3: pdf.
Homework 4: pdf.
These are the "homework" exercises for a week-long
instructional workshop for graduate students
co-organized with Andreatta and Schoof in May, 2005.
These were too many exercises for the amount of time given.
But if you have more than a week to spend on them then
perhaps some of the exercises will be helpful or interesting if you
are taking your first steps in this direction. Since
the lectures that naturally accompany these exercises
are not recorded here, a recommended substitute is some of the
written lecture notes from the ``Notes on complex multiplication''
(see above) and a lot of asparagus.
What do these 5 people have in common?
Draft of Andreatta's notes for course at 2009 CMI summer school